The explosion is believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 mi) above the Earth‘s surface. Different studies have yielded varying estimates of the object’s size, with general agreement that it was a few tens of metres across.”

During the Apollo mission to the moon, the astronauts set up several mirrors on the surface of the moon. The McDonald Observatory near Ft. Davis, TX would shoot laser beams at those mirrors to measure the distance between the Earth and the moon with an accuracy of centimeters! They determined that the moon was indeed hit by a comet several centuries ago, as observed by some monks in Canterbury, England, based on the slight movement of the moon. http://mcdonaldobservatory.org/images/research/waad/d_mcd-1.jpg

Venus, our sister planet in terms of size, is covered in Carbon Dioxide clouds and is as hot as hell. The thick clouds increase the greenhouse effect on that planet, preventing the infrared waves from escaping its atmosphere and effectively warming the planet. A little greenhouse effect is a good thing, because without it on Earth, all of our water would be ice.

Astrology and Astronomy were once united in popular culture and remained so in the eyes of the church and scientists such as Ptolomy. It wasn’t until the end of the Dark Ages was this no longer the leading thought. In this episode, Sagan tells the biography of Kepler, the man who quantitatively defined eliptical planetary motion.

Surely with a billion trillion stars and other planets in existence we are not the only one with living organic matter. In this episode, Sagan illustrates the beginnings of the universe on a calendar with the time of humans comprising the last seconds of December 31 (and the Big Bang occurring on January 1st). He also briefly describes evolution and natural selection and provided a very interesting history of our evolutionary ancestors. The history of Earth is also delved into. Was RNA the very first living molecule on Earth?

To commemorate the awesomeness of Carl Sagan and to celebrate his birthday, I have decided to watch all of Cosmos this week (13 episodes). I slacked yesterday so three episodes are in store for today. I just finished Episode 1. The first half prepares you for thinking about the cosmos, Greek for order and the interconnectedness of all things. Thinking about the cosmos is similar to thinking about geology in terms of the sheer immensity of time and the insignificant amount of time we spend on Earth. The rocks around us are millions of years old and the stars we see in the sky are billions of light-years away. It’s difficult to wrap one’s head around something like that. We are also introduced to the spaceship of the imagination, a module of intergalactic travel shaped like a dandelion seed. The spaceship and Sagan’s acting on it is corny upon first seeing it (what wasn’t corny in the seventies? Haha) but deeper into the series, the spaceship becomes a trademark and one of my favorite things. In episode 1 Sagan also tells us of the library of Alexandria, an incredible store of knowledge which is now lost, and also Eritosthenes (sp?), an Egyptian jack-of-all-trades who measured the circumference of the Earth using the sun, some sticks, and his brains. And all of this is just a preview of what is to come!